Dear Ed,
Glycerol is a solubilizing agent. Unless something is done to conteract
such effect
the crystals will dissolve. Laura Vera from my lab made a presentation at
ICCBM-14
on this subject.
We have developed a set of balanced solutions, mixed solubilizers like
glycerol and ethylene
glycol with precipitants like MPD, DMSO and neutral compounds like
di-ethylene glycol
and propanediol that with PEG and salts crystallization conditions take
out the guesswork
from designing cryo-conditions.
The mixed conpounds are marketed by Molecular Dimensions
google search: CryoProtX
Before ordering the kit check that the crystals do not dissolve with MPD.
If crystals crack
but do not dissolve with MPD (it may be worth ordering the kit). Cracking
is good since it means
that the crystals do indeed dissolve in glycerol because of glycerol's
solubilizing properties.
Now try Propylene glycol (1,2-propanediol).
This is a neutral single component. It is a good starting point to work on
your cryo-conditions
which you will then be able to improve when you have all the various
cryo-components and
premixed combinations.
The paper for the mixed cryosolutions will be submitted to the ICCBM-14
special issue
of the Crystal Growth and Design probably this week.
polyacrylic acid is a novell precipitant, make sure that you keep
magnesium in your
cryosolution. I would also check if increasing the magnesium concentration
in the
cryoprotectant solution might not be beneficial.
Enrico.
On Wed, 17 Oct 2012 06:01:08 +0200, Edward A. Berry <[email protected]>
wrote:
Would someone suggest a cryoprotectant for index screen #59? It contains
0.02 M MgCl2
0.1 M HEPES pH 7.5
22% polyacrylic acid 5100, Na salt
Adding glycerol tends to dissolve the crystals.
Thanks,
Ed
--
Enrico A. Stura D.Phil. (Oxon) , Tel: 33 (0)1 69 08 4302 Office
Room 19, Bat.152, Tel: 33 (0)1 69 08 9449 Lab
LTMB, SIMOPRO, IBiTec-S, CE Saclay, 91191 Gif-sur-Yvette, FRANCE
http://www-dsv.cea.fr/en/institutes/institute-of-biology-and-technology-saclay-ibitec-s/unites-de-recherche/department-of-molecular-engineering-of-proteins-simopro/molecular-toxinology-and-biotechnology-laboratory-ltmb/crystallogenesis-e.-stura
http://www.chem.gla.ac.uk/protein/mirror/stura/index2.html
e-mail: [email protected] Fax: 33 (0)1 69 08 90 71
